Firearm



A. V. P. M. BERTHIER.

FIREARM.

APPLICATION FILED MAY28,1917.

Patented Jan. 25,1921.

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FIREARM.

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stre ar ANDR vraertn rAUL MARIE Bnncnnrnn, or NEUILLY-snR-SEINE, VFRANCE, AssrGNOn 'ro UNr'rnn srArns MACnrNE GUN COMPANY, or BOSTON, MASSA? cnnsnfr'rs, A CORPORATION or MASSACHUSETTS.

FIREARM.

Specification of Letters Patent.

Application inea may 2s, 1er?.v serial No. 171,373. i

I' To Vall whom 'it 'may concern:

Be it known that 1, ANDRVIRGILE FAUL MAnin Bnn'rninn, a citizen of the Republic of France, and aV resident of Neuilly-sur- Seine,l in the French Republic, (whose postoitiee address is 15bis Rue d `Orlans, Neuillysur-Seine, France, )A have invented an lmprovement in Firearms, of which the following description, in connection vwith the accompanying drawings, is a specification, like characters on the drawings representing like parts.

This invention relates to fluid operated apparatus and has for its object more particularly to provide means whereby the Huid low or pressure may be controlled or variably adjusted as circumstances may require.

it is a well known `tact that the efficiency of fluid operated apparatus varies and may be seriously affected by changes ot conditions. Thus it has been found that the operation of gas operatedfrearms, such as machine guns, is appreciably aected by changes in climatic conditions and Achanges of altitude, particularly the latter. lt is found, tor example, that as the altitude at which a gas operated machine gun is operatedY increases, the eiiiciency ot the gun de-v creases in proportion, and if the change from a lcwerto a higher altitude is sutliciently great the gas pressure which served for etlicient operation .of the gun at the lower altitude will no longer SuiCe, the

speed of operationot the gun, torve'xample, falling o5 to such a degree as vgreatly to impair its ,eiectiveness My invention, by rendering the Vgasflow orpressure adjustable overcomes this detect.

The objects andaims of the invention willi bestbe understood from the following description, taken'in connection with the accompanying drawings,'o't several forms or embodiments ot' the invention shown and described for illustrative purposes, it 'being understood that the invention in its true scope is definitely set forth by the claims.

n the drawings: Figure 1 is a longitudinal, vertical, secticnalelevation of thebreechl portion of a machine gun containing the operating mechanism;

Fig. Q -is a longitudinal, vertical section through the barrel and part of the operating mechanism of a machine gun, and showing one illustrative embodiment of my invention applied thereto;

Fig. 3 is a side elevation of said embodiment of my invention; 4

Fig. 4 is a vertical cross section on line 4-1 of Fig. 3;

Fig. 5 shows the breech block and lextractor;

Fig. 6 is a sectional detail of the breech block', firing pin, gas piston and connecting parte 0n1ne6-6of Fs.- 1 ;v l Fig. 7 is a detail ot the means for retaining the cylinder 154e in place; f

Fig. 8 shows vaiurther illustrative embodiment of my invention;

Fig. 9 shows a further illustrative embodiment of my invention in which the radial passages in the cylinder 154 are arranged in Vdifferent transverse planes or substantially in a helical line or plane;

Fig. 10 shows a key which may be used to rotate the cylinder 154; andl Fig. 11 shows said key in use.

My inventionis herein conveniently shown applied to. the machine gun `of my Patent No. 1,083,872 of January 6, 1914, but it will be apparent that myV invention is equally applicable to Vanyother gas operatedmachine gun. e Only somuch ot the mechanism and vstructure ot thel gun and its mode of operation will be described herein as is necessary to an .understanding o1" the `present invention, being understood that the said structure, mechanism and mode of Operation are fully described in my patentabovereterred 'to, to which reference is made for a moredetailed description thereof.

ln the embodiment yofthe invention herein shown, a portion of the `gases generated by the. explosion pask @from the ha@ .2, Fig.. 2, of the barrel@ throughapassage Ltinto a gSCllamber or cylinder 6 iny which l is/van actuating member to be operated by said gases, said member herein .consisting ,cfa piston 8 having a reduced head 1() o d1- ameter to fit closely within the fore part 12 of the cylinder 6 when said piston is in its 'forward position. VvT he passage 4 is provided is bored at 16 to receive a helical spring 18 which bears at its front or right end, referring to Fig. 1, against the bottom of said bore, and at its rear end against a part of the frame 20 of the gun. A pin 22 screwthreaded into the frame at 24 extends into the bore 16 of the piston and for a certain distance within the spring 18, to serve as a guide for the latter when the piston is driven forward by its spring.

The breech block 26 is reciprocated within the frame 28 by the piston 10 and is suitably guided withinY said frame,'all as fully eX- plained in my patent above referred to. To reciprocate the breech block, the piston 10 is L provided near its rear end, Fig. 1, with an upwardly projecting plate 30 having upon each side near its upper end a laterally projecting nipple 32. The plate 30 extends upwardly between two parallel plates 34, 34 extending downwardly from the cylindrical vportion 36 of the breech block and each provided with a slot 38, each of said slots being adapted to be engaged by one of the nipples 32, see Fig. 5. The opening of said slots 38, both vertically and horizontally, is somewhat greater than the height and width of said nipples 32, and from eazh of said slots there extends downwardly in an inclined direction to the front edge of each of the plates 34, a guide groove 40, the lower edges 42 of said grooves starting from the lower edges of the slots 38, 38, but the upper edges 44 of said grooves 40 starting slightly below the upper edges of said slots 38, 38,

thus leaving a shoulder 46, 46, adapted to be' engaged by said nipples 32, it being understood that the guide grooves 40, 40 are of a width to allow tree passage along them of said nipples 32, when the latter are in the lower ends of the slots 38.

The tiring pin 48 is mounted for sliding movement in a suit-able chamber 50 provided in the breech block 26, and when projected forwardly its front end 52 projects sun"iciently from an opening 54 of the breech block to explode the cartridge 'that is in the cartridge chamber of the gun, a shoulder 56 upon the tiring pin cooperan ing with a shoulder 58 of the breechblock to limit the forward movement of the firing pin in the latter. Movement of the ring pin 48 in the breech block is effected by the piston 10 by means of the plate 30 which is loosely einbrared between two abutments 60 and 62 extending downwardly from the firing pin l48 into the space between the two plates 34, 34 through a longitudinal opening in the front end abutment of the main body of the breech block, which latter is adapted to swing about said pivot 66, while the head 64 moves in a suitable guide provided in the casing 28 and has no vertical movement, all as fully eX- plained in my patent above referred to. The two parallel plates 34, 34 extending down` wardly from the breech block are connected at their rear lower ends by a transverse wall 72, with which a projection 74 on the piston 10 cooperates torassist in the forward 1novement of the breech block by the piston. Rearward movement of the breech block is effected by a shoulder 76 which coperates with a downwardly projecting abutment 78 on the breech block, through an elastic buffer 80. The breech block is provided upon its under side with an inclined cam surface 82 forward of the abutment 78 and upon its upper surface with a projection 84, the functions of which will be hereinafter more fully described.

The trigger mechanism consists of a recessed sear 86 which is adapted to oscillate upon a pin 88 and whose rear arm is provided with a plate 90 acted upon by a spiral spring 92. This sear engages a tooth 94 on the under side of the piston in the case of individual tiring. A second sear 96 pivoted at 98 carries the trigger 100 and is acted upon at its rearend by a spring 102. This scar 96 carries between the point where it is acted upon by the spring 102 and its pivot 98, a reinforcement 104, having a recess to receive one end of a spring 106, the other ond of which is received in a recess provided in a catch 108, which is adapted to swing about a pivot pin 110. This sear 96 cooperates with a tooth 112 situated back of the tooth 94' upon the under side of the piston 10. Y

The cartridges are contained in a magaeine 114 which is inserted from above into a bearing` sleeve 116, the cartridges being pressed downwardly by a fan-shaped spring 118 acting upon a l'ollower120 and arepresented successively one by onein the path of movement of the breech block 26. F or a full description of the construction of the magazine and its operation, reference may be had to my patent above referred to. A more detailed description thereof is not deemed necessary herein for the understanding of the prese -t invention.

A cartridge extractor 124 is mounted on thebreech block by means of a pin 1264 which engages'in a curved recess 128 in the breech block in such manner that the breech block can ascend and descend independently of the cartridge eXtractor which is guided during its entire course in a longitudinal serves to take up the pull in withdrawingthe cartridge case. This extractor is constructed and operated as described in the patent above referred to, to which reference is made for a moredetailed description.

VThe gunrmay be provided with a sliding cocking handle 122, suitable cooling means, shooting sta-y, etc., all of which may be of the construction and'mode of operation described in my patent above-referred to and need not be herein more fully described.

The gun is adapted for individual firing as well as for automatic firing, and for this purpose is provided with Va rotary ley 134 provided with shoulders 186, 136. When this key is4 turned into the position shown in Fig. 1, one ofthe shoulders 186 engages the scar 86 and presses it downwardly so as i to hold it out of engagement with the tooth 94; 1n this condition, therefore, only the sear 96 controls the piston by its engagement with the tooth 112 and the gun is adjusted for automatic tiring. With the rotary lkey 134 turned so that neither of the shoulders 186,- 186 is in engagement with the Sear 86, the piston is controlled by the engagement of both `sears with their respective teeth 94 and 112 and the gun is adjusted for individual firing. l

assuming that the gun is adjusted for individual firing, pressure of the finger on the trigger 100 causes the front end of the sear 96 to swing downwardly and the catch 108 to lift the rear end 90 of the Sear 86 thus disengaging the sear 86 from the hook 94 of the piston. The spring 18 moves the piston forward until the tooth 112 engages the sear 96 which is still in its path of movement. Continued pressure on the trigger, however, disengages the sear96 from the hoo'k 112 and the piston l10 is driven forward to its full extent by the spring 18. Furthermore, as the Sear 96 releases therlioolr 112, or immediately thereafter, the catch 108 releases, in thevcontinued backward movement of 1the trigger 100, the rearv fend 90fof the, sear 86, so that the scar 8 6 is 'now free to rise into its original position under the action of` its lspring 92, and is thus prepared to recngage the tooth 94 on the piston when the latter isV returned to its initial position upon theV iir-Y ing of the cartridge. o s I As the piston is `driven forward, as described, by the spring 18, the projection 74 by its engagement withfthe part 72 of the breech block and the nipples 32 by their engagement with the shoulders 46, 46 on said breech block (Fig. 5) carry the breech block 26 forward in a rectilinear directionl until the inclined plane 8201i lthe lower side of the breech block just in front of the abutment 78meets the end 138 of the stationary part 140 of the breech cylinder bearing. Hereupon, the inclined plane 82 slidingup onto' `said part 140 raises the rear end ofthe breech block by turningit abot the pivot or pin 66, suiiiciently to vrelease the nipples 32 from engagement with the shoulders '46, 46 at the upper end of the slots 40, the forward end of the breech block having driven the cartridge home into the cartridge chamber 142 and the front end of said breech bloclr being against and closing the entrance lto the cartridge chamber and the projection 84 being in vertical alinem'ent with correspondingly shaped recess 144, in the frame28. rl`he firing pin 48, which was carried forward with the breech block, has maintained its rearward position therein, but in the continued forward movement of the piston 10, after the breech block has reached the limit of its forward movement as described, the nipples 82 slide along within the inclined slots 40' provided as described inthe plates 34, 34 of the breech block, carrying the firing p in 48 forward with them by their engageinent with the abutment 60 projecting downwardly from said firing pin. ln their move-v the projection 84 within the/recess 144 of the trame,- tlius l'oclrin'gthe breech block against rearward movement, and then project the front end 52 of the ring pin through the opening 54 in theifront end of the breech block and into contact with the primer of the cartridge, thus exploding the latter. A part ofy the explosion gases passes from the bore 2 through the' passage 4 (Fig. 2) into the fore part 12 of the cylinder 6 and thus'drives the piston 10 to the rear against the action of the spring 18 into the position shown in Fig. 1, when the sear 8,6 snaps upwardly in front of the tooth 94 and holds the piston in its rearward position, the gases escaping from the cylinder 6 through the openings 146. The triggerfbeing released, the sear 96 is A returned to its normal position by the spring wardly along the slots 40, thus withdrawing the firing pin 48 into the breech block and by their engagement with the lower inclined edges 42 of said slots lowering the rear end of the breech b locl'r abont'the pivot 66 to disengage the projection 84 on said block fromv the recess 144 of the frame, and the buffer 80 on the projection6 of theV piston then engages the abutment 7 8 on the breechblock andV carries the latter back to its rearward position shown in 1, the projection 74 engaging behind the part 72 of said breech block and the nipples 32 behind the shoulders 46, 46 at the upper ends ofthe 'slots 40, ready to carry the'breech block forwardV again when the trigger is again pulled, another cartridge Vhaving meanwhile-` been Vbinught into position by the's'pringv118 to .shoulders 186 thereon engages the sear 86 and presses it downwardly so as to prevent it from engaging with the piece 94. It the trigger be now pulled back, the sear 96 by which the piston is now controlled will be disengaged from the tooth 112 of the piston, and the piston will continue to reciprocate and the above described movement of the mechanism will be repeated as long as the pressure on the trigger continues, or as long as there are cartridges in the magazine. TWhen the last cartridge is ejected,'the piston comes to restin its forward position and the mechanism is then cocked again by the aid of the cocking handle 122, which is slidingly mounted on the underside of the frame (Fig. 1) and is provided with a projection 148 adapted to engage a projection 150 on said Vpiston 10, so that by pushing the handle 122 backwardly the piston will be returned to its rearward position and then held by the scar,

all as fully described in my patent above referred to.

In Figs. 2, 8 and 4 is shown means for adjusting or varying the flow or pressure of the operating gases for the piston 10, said means herein comprising throttling means. Said throttling means may Vcomprise an adjustable member, which in that illustrative embodiment of the invention,

shown in said figures consists of a cylinder 154 fitted for rotary movement in a transverse cylindrical opening 152 provided in the block 14. Said cylinder is provided with a central bore 156, open to atmosphere at both ends, which may be the right end referring to Fig. 4. With this central bore 156 of the cylinder 154 there communicate a plurality oi? passages extending radially from said central bore 156 to the periphery of the cylinder 154. These radial passages are located in the same transverse plane of the cylinder 154 and are of different diameters. Herein seven such radial passages 158, 160, 162, 164, 166, 168 and 170 are provided, but it will be apparent that this number may be varied as umay be desirable. A passage 172 leads from the passage 4 to the cylindrical opening 152 in which is fitted the cylinder 154, and by rotating said cylinder the outer end of any one of the radial passages 158 .to 170 may be caused to register with said passage 172. The cylinder 154 is provided with afianged head 174 by which it may be readily rotated. Means are provided to hold or lock the cylinder 154 in place when any one of the passages 158 to 170 are in register with the passage 172, said means corresponding to the passages 158 to 170,

respectively, and disposed in such manner about the periphery lof the head 174 that when the pin 17 6 is in engagement with one of said notches the corresponding radial passage in the cylinder 154 is in register with the passage 172. The pin 176 is guided for longitudinal movement in the block 14 and is provided with a collar 194 between which and the base of the opening-in which said pin is mounted there isinserted the helical spring 196 that tends to press the pin outwardly to cause its head to engage any one of the notches 180 to 182 when said notch is brought into register with lthe head of said pin by rotation of the cylinder 154. To rotate the cylinder 154 it is only necessary to press the pin 176 inwardly against the action of the spring 196 to disengage the head of the pin from that notch in the periphery of the cylinder head 174 with which it is in engagement.

The invention contemplates means for rotating the cylinder 154 when adjustment of the gas pressure is desired, said means being useful at all times but particularly when the cylinder has become heated by the firing of the arm. Said means is preferably adapted also to release the pin 176 from locking engagement with the cylinder head 174, to render rotation of the cylinder possible and to that end said means may conveniently consist of a key substantially as illustrated in Figs. 10 and 11. Referring to said figures, in the illustrative form of the key shown herein, the latter comprises a cylindrical stem or shank 170a having a transverse piece 173 to act as a handle and a bit 175. In use the end 177 of the stem 170i is inserted in the central bore 156 of the cylinder 154 at the flanged end of the latter, and theend of the bit 175 of said key is applied to the outer end yof the blockin pin 176 so that, by pushing the end 177,0 the key stem 17()EL home into the bore 156 of the cylinder, the bit `175 of the key will push the pin 176 out of engagement with that notch of the cylinder head 174 with which it is in engagement, as shown in Fig. 11. rl`he bit 175 of the key being now in engagementwith the notch vacated by the pin 176, by turning the key the cyllnder 154 can be turned until the next following notch in the head of said cylinder comes into alinement with the pin 176, whereupon the latter will engage said notch under the action of its spring 196 and arrest further rotation of said cylinder. In this way the cylinder 1,54 can be turned step by step to bring any one of its radial passages 158 to 170 into alinement with the passage 172.

A passage 179 will preferably be provided in the block 14, said passage being in axial alinement with the passage 172, see Fig. 2, This passage 179 facilitates the boring of the passage 172, the boring tool beinginserted through the passage 179, the cylinder 154 having been previously withdrawn, and the passage 172 being then readily bored in alinement with said passage 179. rhe'passage 179 also greatly facilitates cleaning of said passage 172 and ot the radial passages 158 to 1700i the cylinder 154, for by turning said cylinder said radial passages may be successively brought into registerv with said passage 179, and any suitable cleaning tool may then be passed through said passage 179 and the radial passage in register therewith to clean the latter. Y

Accidental withdrawal of the cylinder 154 from the block 14 is prevented by a spring pressed pin 198 mounted for sliding movement in a bore 200 and having its outer end normally maintainedby the action of its spring V199 in engagement with an annular,

groove 201 provided on the periphery of the cylinder 154. The pin 198 is provided with a tinger piece 202 projecting outwardly through a slot in the wall of` the block 14, by

which the pin 198 may be pushed outwardly to withdraw its end from engagement with the groove 201 ott the cylinder 154, thus enabling the latter to be removed for cleaning or Jfor any other purpose. That portion ot the wall of the block 14'tlirough which the inger countersunlr to protect said nnger piece from accidental contact in the use of the gun.

lt will be seen from the above-described construction that at each discharge ot' the gun a certain amount o'l the gases generated by the explosion passes from the bore 2 of the barrel through the passage 4 into the front endg'12 ot the cylinder to drive the pistonlO rearwardly, a certain part of said gases being exhausted into the atmosphere through the passage 172, that one of the assages 158 to 170 which is in register therewith, and the axial opening or bore 15601i the cylinder 154. By varying the amount ot the gas thus exhausted, which is herein etected by bringing the radial passages 158 to 170 of different diameter into coincidence with the passage 172, the amount kof the gases entering the cylinder 6 through the passage 4 will also be varied. y

Y It will thus be seen that this invention provides means whereby the gas pressure for operating the apparatus or gun may-be controlled or adjusted as desired. The pressure may be lvaried or adjusted to preserve the same gas pressureV and therefore the same etfectivenessof operation at whatever altitude the gun is used.

piece 202 projects will preferably bel The smaller the amount ofthe gases that is allowed to exhaust through the passage 172, the greater will the amount ot the gases be that penetrate into the cylinder 6 from the barrel and the greaterv therefore will be the force exerted byV said gases upon the piston 10. `As the altitude at which the gun Yused increasesthe greater must the gas pressure be in ordereffectively to operate the gun, and therefore while at sea level the cylinder 164 will be adjusted kwith the passage 170 in alinementwith the passage 17 2, it will be found that as the altitude increases one of the passages 168 to 158 of less diameter according to the altitude attained, should be used. l Y

lt will thus be seen that my invention is particularly valuable in machine guns mounted on aeroplanes. s

@ther conditions may also effect the gas pressure, for vexample changes of climate or variations in the quality of the ammunition used, but all variations in the gas pressure whether caused by the conditions enumer- Y ated or any others may be quickly remedied by the use of my invention and that gas Y pressure secured or maintained as is leest suited for the effective operation of the gun.

In Fig.s8, a modified construction is shown. Here the radial passages 158'to170 in` the cylinder 154V are replaced byv peripheral grooves 203, 204, 205, 206 and 208, which by rotation of the cylinder 154 may each be brought into alinement with a passage 210 extending from said passage 4 transversely of said cylinder 154 in the same transverse plane as said grooves 203 to 208 and opening into vthe atmosphere at 212. Said passage 210 intersects the cylinder 154 substantially to the width of' said passage. 1n all other respects, the construction may be the same as that shown in Figs. 2 to 4.

It will be seen that the shallowest groove in A `the latter has screw-threaded engagement at 181 with the screwfthreaded inner wall of the cylindrical opening 152. the pitch of the screwrthreads and that of the helical line in which the radial passages 158 and 17 0 are disposed being thesame. Allhen the cylin-Y der 154 is screwed entirely home, none of the radial passages158 to 170 coincides with the passage 152, the latter being thus Vclosed by the Wall of the cylinder 154, but by unscrewing the cylinder said radial passages may be brought successively to coincide with said passage to vary the gas pressure, said radial passages being of course of different diameter as in the construction previously described, herein seven radial passages are .provided With corresponding notches upon the periphery of the head 174 to be engaged by the pin 176 and hold the cylinder in adjusted position, and also the axial bore 156 in said cylinder into Which the helically arranged radial passages open. In this construction, the pin 198 and annular groove 201 may be omitted, as the screw threaded engagement of the cylinder with the block 14, in conjunction With the engagement of the locking pin 176 With the notches in the fianged head 174 of the cylinder prevent accidental Withdrawal of the latter.

The gun may be used with the cylinder 154 screwed home, that is to say with the passage 172 closed Where conditions Warrant it.

It Will be apparent that in the construction shown in Fig. 9, the radial passages in the cylinder 154 could be replaced by the peripheral passages or grooves shown in Fig. 8, said peripheral grooves being however disposed in a helical line around the periphery of said cylinder.

he gas or pressure controlling means embodying my invention is simple in construction and operation. There are no parts to get out of order, and the cylinder 154 is easily and quickly removable, and When removed the parts are readily accessible for cleaning. The cylinder is as easily and quicklyl replaced and there is practically no chance of its being accidentally displaced after it has been adjusted in the position desired.

It Will be apparent that While the invention has herein been described as embodied inthe details illustrated, the invention is not to be considered as circumscribed or limited to these details, or any of them, since they may be variously modified Within the true scope of the invention which is definitely set forth by the claims.

Claims.

1. In a gas-operated firearm, in combination, means actuated by the explosion gases to operate the firearm; conducting passages to conduct the gases from the bore of the firearm to said actuating means and to theatmosphere; and a gas pressure controlling member adapted to coperate with one of said conducting passages and provided with a plurality of passages of different diameter disposedv in different transverse planes, said controlling member being rotatable and movable axially to cause any one of its passages to coperate with said conducting passage.

2. In a gas-operated firearm, in combination, means actuated by the explosion gases to operate the firearm; conducting passages to conduct the gases from the bore ofthe lirearm to said actuating means and to the atmosphere; and a gas pressure controlling member adapted to coperate with one of said conducting passages and provided With a plurality of radial passages of different diameter disposed in different transverse planes, said controlling member being rotatable and movable axially t9 cause any one of its passages to coperate with said conducting passage. a

3. In a gas operated firearm, in combination, means actuated by the explosion gases of the firearm toloperate the latter; a casing; gas passages leading from the bore or the firearm to said actuating means and to the atmosphere; a gas pressure controlling rotary member provided With a plurality of passages of different diameter disposed in a substantiallyhelical line in said member, said rotary member having screw-threaded connection with said casing, by means of a screw-thread of substantially the same pitch as that of the helical line in which the passages are disposed in said member, so that by rotation of said member any one ofthe passages therein may be caused to coperate with said conducting passages; and means to lock said rotary member in adjusted position. Y

4. ln a gas-operated firearm, in combination, means actuated by the explosion gases of the firearm tovoperate the latter; a casing; gas passages leading from the bore of the firearm to said actuating means and to the atmosphere; a gas pressure controlling rotaryV member provided with av plurality of radial passages of different diameter disposed in a substantially helical line in said member, said rotary member having screwthreaded connection with said casing, by means of a screw-thread of substantially the same pitch as that of the vhelical line in which the radial passages are disposed in said member, so that by rotation of said member any one of the radial passages therein may be caused to coperate with said conducting passages; and means to lock said rotary member in adjusted position.

5. In a gas-operated firearm, in combination, a gas cylinder; a piston contained in said cylinder and adapted to be actuated by the explosion gases from the bore of the firearm; a passage leading fromV said bore to said cylinder; means, including an adjustable rotary cylinder provided with a plurality of passages of different diameter disposed in a substantially helical line in said rotary cylinder, for varying the amount of explosion gases acting upon said piston, said rotary cylinder being also movable axially to cause any one of its passages to coperate with the passage leading from the bore of the rearm to the gas cylinder; and means to lock said rotary cylinder in adjusted position.

6. ln a gas-operated firearm, in combina` tion, a gas cylinder; a piston contained in said cylinder and adapted to be actuated by the explosion gases `from the bore of the iirearm; a passage leading from said bore to said cylinder; means, including an adjustable rotary cylinder provided with a plurality ofV radial passages er' dierent diameter disposed in a substantially helical line in said rotary cylinder, for varying the amount of explosion gases acting upon said piston, said rotary cylinder being also movable axially to cause any one of' its radial passages to coperate with the passage leading from the bore of the firearm to the gas cylinder; and lmeans to lock said rotary cylinder in adjusted position.

7. In a gas-operated firearm, in combination, means actuated by the explosion gases of the firearm to operate the latter; adjustable means to vary the amountof the explosion gases acting upon said operating means; means to retain said adjustable means in adjusted position; and a combined releasing and adjusting key, separate from the firearm and constructed and arranged to be applied to said adjustable means and when applied thereto to engage and release said retaining means and engage said adjustable means so that it can be adjusted by said key.

8.1m a gas-operated firearm, in combination, means actuated by the explosion gases of the rearm to operate the latter; a conducting passage leading from the bore of the firearm to said operating means; a rotary cylinder provided with a plurality of passages Vor different diameter, each of which can 'be caused to ooperate with said conducting passage by rotation oi said cylinder; means to lock said cylinder in adjusted position; and means separate from said firearm and constructed and arranged to be applied to said cylinder for first releasing said locking means and then turning said cylinderto bring one of the passages in the latter out of cooperation with said conducting passage and bring another into cooperation therewith.

9. ln a gas-operated firearm, in combination, means actuated by the explosion gases of the firearm to operate the latter; a conducting passage leading from the bore of the firearm to lsaid operating means; a rotary cylinder provided With a plurality of passages of different diameter, each of which can be caused to cooperate with said conducting passage by rotation ot said cylinder; a locking pin automatically to engage a notch in the periphery of said rotary cylinder and lock the latter in place, whenever one of the passages in said cylinder is in position to cooperate with said conducting passage; and means tor first disengaging said pin from the peripheral groove of said cylinder and then rotating the latter to cause another passage therein to cooperate with said conductive passage.

l0. ln a gas-operated firearm, in combination, operating means adapted to be actuated by pressure ot' the explosion gases to operate the firearm; and means, comprising a member provided with a plurality of gas passages disposed in different transverse planes, said member being adjustable to render said passages selectively operative to vary the gas pressure acting on said firearm operating means.

1l. ln a gas-operated firearm, in combination, means actuated by the explosion gases to operate the firearm; gas passages to conduct the gases from the bore of the firearm to said actuating means and to the atmosphere; and a gas pressure controlling member adapted to coperate with one of said gas passages and provided with a plurality of passages of different diameter disposed in different transverse planes, said controlling member being adjustable selectively to cause any one of its passages to cooperate With said gas passage.

In testimony whereof l have signed my name to this specification.

ANDR VlRGlLE PAUL MARIE BERTI-HER. 

